Typically when a presidential candidate wraps up his party's nomination after months of reaching out to base voters in the primaries, the question becomes whether he can appeal to the political center for the general election.

Not for Mitt Romney.

Rick Santorum had barely left the stage when a different question loomed. Can the former Massachusetts governor -- who famously shifted his position on abortion and other hot button issues -- rally skeptical social conservatives in his own party?

The answer to that question -- which will have major ramifications in November -- appears uncertain.

The Family Research Council's Tony Perkins told CNN minutes after Santorum suspended his campaign there is such a lack of enthusiasm for Romney that social conservative grass roots operations will likely turn away from the presidential race and towards efforts to put the Senate in GOP hands.

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Other longtime conservative activists say Romney still has plenty of time to get them excited.

But he has to work at it.

Veteran conservative strategist Ralph Reed is one of many who told CNN Romney "has some more work to do."

Where should his focus be?

Appeal to evangelical voters through "general election messaging, the vice presidential selection, and the convention acceptance speech," said Reed, who stressed he is "confident both Gov. Romney and his campaign know they have to build bridges to conservatives, and will work diligently to do so."

Not all conservative activists are so sure.

"I would not refuse to talk to him. It's not too late necessarily, but I don't know what he could say to me that would make me feel better," said Michael Farris, who heads a home school grass roots organization that gets out the vote for GOP candidates.

Farris told CNN that if the election were held today, he would hand in a blank ballot.

He says Romney's "propensity to change his story" on issues important to social conservatives, like abortion, is a problem.

"If I were advising him, I'd be looking for some issue to reach out the conservatives with. But he needs to have an issue where people can't say it's one more flip flop," said Farris.

"A Republican presidential candidate can't win without a fully mobilized evangelical base. It's impossible for Romney to win the general election without evangelicals," said Farris.

Steve Scheffler is a longtime social conservative activist in Iowa, which will be a battleground state in the general election.

He told CNN his Iowa Faith and Freedom Coalition invited Romney to two presidential forums last year, and he "refused to come."

Scheffler said Romney has done "absolutely nothing" to reach out to the base, which he called a huge mistake.

"I don't think the Romney campaign has any room for error" in the general election.

Like other conservative leaders, Scheffler said the issue isn't so much whether conservatives already going to vote will check the box for Romney over President Obama. The issue is whether people are going to get out and work for him -- providing critical grass roots energy fueled by the kind of passion that can mean the difference between winning and losing.

"95% of the people that are going to man your phone banks are not the old party hacks, they're the conservative activists. Who's going to man the phone banks?" Scheffler asked.

"It's very dangerous to proceed with an arrogant attitude," he stressed.

But in an editorial board meeting with CNN, Southern Baptist Convention leader Richard Land had a different perspective.

"I think that Romney will get the support of most social conservatives and the enthusiastic support of most of them unless he drives them away - unless he picks a non-social conservative running mate, he doesn't talk about our issues or gives any indication he's going to soft pedal our issues when it comes to places of influence in a Romney administration," said Land.

Land said he knows Romney "fairly well" and insists he is misunderstood.

He said he believes Romney's transition from pro-abortion rights to anti- abortion was genuine, not a politically motivated flip-flop.

Land called Romney a "data guy" and described a story Romney told him about deliberating over whether to approve embryonic stem cell research as Massachusetts governor.

Land said Romney looked at information that made the governor believe an embryo is human life.

Land doesn't endorse candidates, but insisted that intense opposition to Obama will boost support for Romney.

"Obama does the motivation for us," said Land.

Land described the president's caught-on-camera remarks to Russia's leader promising to be flexible after the election as a major motivator that "reverberates, reverberates and re-reverberates in the conservative community."

"It feeds into their fears and suspicions that inside Barack Obama is a radical waiting to get out the day after he is elected to his second term and is no longer accountable to the voters," said Land.

Reed told CNN anti-Obama fervor not enough.

"Mitt Romney will win the support of evangelicals and conservatives because his opponent is Barack Obama. But he needs the grassroots enthusiasm of activists who are for him, not just against Obama," said Reed

Multiple conservative leaders compared Romney's problem with conservatives to troubles John McCain had in 2008, which he helped solve by picking Sarah Palin, a conservative rock star, as his running mate.

Land dismissed the analogy in colorful, personal terms, saying there are more "positive feelings" towards Romney now than there were at this point in the 2008 cycle towards McCain.

"He's a more likable guy. I mean McCain, even McCain's friends don't like him much. His nickname was McNasty when he was in prep school," said Land.

But the data show that Romney actually has less support among evangelical voters than McCain did.

A CNN/Opinion Research Corp. poll taken late last month shows Romney with 63 percent of the white, born-again Christian vote in a matchup against Obama.

The same poll taken at roughly the same time in 2008 showed McCain with 72 percent support from white, born-again Christian voters.

What all conservative activists agree on is how critical Romney's vice presidential pick will be in galvanizing social conservative voters.

"Whether they're going to work hard for him depends on what he does. If he picks a [Florida GOP Sen.] Marco Rubio, or if he picks a [House Budget Chairman] Paul Ryan they're going to work for him," said Land.

Some suggest Romney announce his running mate earlier than usual in order to motivate the conservative base.

In fact, that urgency was shared by multiple conservative leaders and activists contacted by CNN.

One told CNN he would suggest Romney attend the Southern Baptist Convention in June and give a major speech.

"He doesn't need to say anything wacko," said the conservative activist who is sympathetic to Romney and asked not to be identified talking about potentially private advice.

He recommended that Romney go after Obama on health care and other issues, talk about the importance of the First Amendment, and praise Southern Baptists for work with the homeless and other charitable efforts.

When CNN posed the idea to Land, he responded, "That's a great idea."

He described Romney's cure for disenchanted evangelicals this way:

"All he's got to do with the base is pick a pro-life nominee and give signals that he will have an administration that will be pro-life, will undo Obamacare if the Supreme Court doesn't do it for us, will have strict constructionist original intent jurists, (and) will not seek to put distance between the United States and Israel. That's enough," said Land.